LitCharts assigns a color and icon to each theme in The 5th Wave, which you can use to track the themes throughout the work.
Trust and Belief
Survival and Perseverance
Warfare and Dehumanization
Family
Summary
Analysis
Cassie crawls on her stomach through the ventilation system. A cockroach crawls past her. She gets to a place where she can overhear some men talking. They mention someone killing three soldiers. Cassie figures they must be talking about Evan, and that this means Evan is somewhere in the camp. She figures he has disobeyed her and infiltrated the base on his own. Just then, a siren goes off.
A cockroach is small but resilient against human attempts to destroy it. In a similar way, Cassie is nearly powerless against the aliens, but she clings on to survival like a cockroach. The fact that Evan disobeyed Cassie and went against his own kind, risking his life by coming into the camp, reflects how far he is willing to go for Cassie’s sake.